// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/midi/usb_midi_descriptor_parser.h"

#include <algorithm>

#include "base/logging.h"
#include "base/strings/stringprintf.h"

namespace midi {

namespace {

    // The constants below are specified in USB spec, USB audio spec
    // and USB midi spec.

    enum DescriptorType {
        TYPE_DEVICE = 1,
        TYPE_CONFIGURATION = 2,
        TYPE_STRING = 3,
        TYPE_INTERFACE = 4,
        TYPE_ENDPOINT = 5,
        TYPE_DEVICE_QUALIFIER = 6,
        TYPE_OTHER_SPEED_CONFIGURATION = 7,
        TYPE_INTERFACE_POWER = 8,

        TYPE_CS_INTERFACE = 36,
        TYPE_CS_ENDPOINT = 37,
    };

    enum DescriptorSubType {
        SUBTYPE_MS_DESCRIPTOR_UNDEFINED = 0,
        SUBTYPE_MS_HEADER = 1,
        SUBTYPE_MIDI_IN_JACK = 2,
        SUBTYPE_MIDI_OUT_JACK = 3,
        SUBTYPE_ELEMENT = 4,
    };

    enum JackType {
        JACK_TYPE_UNDEFINED = 0,
        JACK_TYPE_EMBEDDED = 1,
        JACK_TYPE_EXTERNAL = 2,
    };

    const uint8_t kAudioInterfaceClass = 1;
    const uint8_t kAudioMidiInterfaceSubclass = 3;

    class JackMatcher {
    public:
        explicit JackMatcher(uint8_t id)
            : id_(id)
        {
        }

        bool operator()(const UsbMidiJack& jack) const
        {
            return jack.jack_id == id_;
        }

    private:
        uint8_t id_;
    };

    int DecodeBcd(uint8_t byte)
    {
        DCHECK_LT((byte & 0xf0) >> 4, 0xa);
        DCHECK_LT(byte & 0x0f, 0xa);
        return ((byte & 0xf0) >> 4) * 10 + (byte & 0x0f);
    }

} // namespace

std::string UsbMidiDescriptorParser::DeviceInfo::BcdVersionToString(
    uint16_t version)
{
    return base::StringPrintf("%d.%02d", DecodeBcd(version >> 8),
        DecodeBcd(version & 0xff));
}

UsbMidiDescriptorParser::UsbMidiDescriptorParser()
    : is_parsing_usb_midi_interface_(false)
    , current_endpoint_address_(0)
    , current_cable_number_(0)
{
}

UsbMidiDescriptorParser::~UsbMidiDescriptorParser() { }

bool UsbMidiDescriptorParser::Parse(UsbMidiDevice* device,
    const uint8_t* data,
    size_t size,
    std::vector<UsbMidiJack>* jacks)
{
    jacks->clear();
    bool result = ParseInternal(device, data, size, jacks);
    if (!result)
        jacks->clear();
    Clear();
    return result;
}

bool UsbMidiDescriptorParser::ParseDeviceInfo(const uint8_t* data,
    size_t size,
    DeviceInfo* info)
{
    *info = DeviceInfo();
    for (const uint8_t* current = data; current < data + size;
         current += current[0]) {
        uint8_t length = current[0];
        if (length < 2) {
            DVLOG(1) << "Descriptor Type is not accessible.";
            return false;
        }
        if (current + length > data + size) {
            DVLOG(1) << "The header size is incorrect.";
            return false;
        }
        DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
        if (descriptor_type != TYPE_DEVICE)
            continue;
        // We assume that ParseDevice doesn't modify |*info| if it returns false.
        return ParseDevice(current, length, info);
    }
    // No DEVICE descriptor is found.
    return false;
}

bool UsbMidiDescriptorParser::ParseInternal(UsbMidiDevice* device,
    const uint8_t* data,
    size_t size,
    std::vector<UsbMidiJack>* jacks)
{
    for (const uint8_t* current = data; current < data + size;
         current += current[0]) {
        uint8_t length = current[0];
        if (length < 2) {
            DVLOG(1) << "Descriptor Type is not accessible.";
            return false;
        }
        if (current + length > data + size) {
            DVLOG(1) << "The header size is incorrect.";
            return false;
        }
        DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
        if (descriptor_type != TYPE_INTERFACE && !is_parsing_usb_midi_interface_)
            continue;

        switch (descriptor_type) {
        case TYPE_INTERFACE:
            if (!ParseInterface(current, length))
                return false;
            break;
        case TYPE_CS_INTERFACE:
            // We are assuming that the corresponding INTERFACE precedes
            // the CS_INTERFACE descriptor, as specified.
            if (!ParseCSInterface(device, current, length))
                return false;
            break;
        case TYPE_ENDPOINT:
            // We are assuming that endpoints are contained in an interface.
            if (!ParseEndpoint(current, length))
                return false;
            break;
        case TYPE_CS_ENDPOINT:
            // We are assuming that the corresponding ENDPOINT precedes
            // the CS_ENDPOINT descriptor, as specified.
            if (!ParseCSEndpoint(current, length, jacks))
                return false;
            break;
        default:
            // Ignore uninteresting types.
            break;
        }
    }
    return true;
}

bool UsbMidiDescriptorParser::ParseDevice(const uint8_t* data,
    size_t size,
    DeviceInfo* info)
{
    if (size < 0x12) {
        DVLOG(1) << "DEVICE header size is incorrect.";
        return false;
    }

    info->vendor_id = data[8] | (data[9] << 8);
    info->product_id = data[0xa] | (data[0xb] << 8);
    info->bcd_device_version = data[0xc] | (data[0xd] << 8);
    info->manufacturer_index = data[0xe];
    info->product_index = data[0xf];
    return true;
}

bool UsbMidiDescriptorParser::ParseInterface(const uint8_t* data, size_t size)
{
    if (size != 9) {
        DVLOG(1) << "INTERFACE header size is incorrect.";
        return false;
    }
    incomplete_jacks_.clear();

    uint8_t interface_class = data[5];
    uint8_t interface_subclass = data[6];

    // All descriptors of endpoints contained in this interface
    // precede the next INTERFACE descriptor.
    is_parsing_usb_midi_interface_ = interface_class == kAudioInterfaceClass && interface_subclass == kAudioMidiInterfaceSubclass;
    return true;
}

bool UsbMidiDescriptorParser::ParseCSInterface(UsbMidiDevice* device,
    const uint8_t* data,
    size_t size)
{
    // Descriptor Type and Descriptor Subtype should be accessible.
    if (size < 3) {
        DVLOG(1) << "CS_INTERFACE header size is incorrect.";
        return false;
    }

    DescriptorSubType subtype = static_cast<DescriptorSubType>(data[2]);

    if (subtype != SUBTYPE_MIDI_OUT_JACK && subtype != SUBTYPE_MIDI_IN_JACK)
        return true;

    if (size < 6) {
        DVLOG(1) << "CS_INTERFACE (MIDI JACK) header size is incorrect.";
        return false;
    }
    uint8_t jack_type = data[3];
    uint8_t id = data[4];
    if (jack_type == JACK_TYPE_EMBEDDED) {
        // We can't determine the associated endpoint now.
        incomplete_jacks_.push_back(UsbMidiJack(device, id, 0, 0));
    }
    return true;
}

bool UsbMidiDescriptorParser::ParseEndpoint(const uint8_t* data, size_t size)
{
    if (size < 4) {
        DVLOG(1) << "ENDPOINT header size is incorrect.";
        return false;
    }
    current_endpoint_address_ = data[2];
    current_cable_number_ = 0;
    return true;
}

bool UsbMidiDescriptorParser::ParseCSEndpoint(const uint8_t* data,
    size_t size,
    std::vector<UsbMidiJack>* jacks)
{
    const size_t kSizeForEmptyJacks = 4;
    // CS_ENDPOINT must be of size 4 + n where n is the number of associated
    // jacks.
    if (size < kSizeForEmptyJacks) {
        DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
        return false;
    }
    uint8_t num_jacks = data[3];
    if (size != kSizeForEmptyJacks + num_jacks) {
        DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
        return false;
    }

    for (size_t i = 0; i < num_jacks; ++i) {
        uint8_t jack = data[kSizeForEmptyJacks + i];
        std::vector<UsbMidiJack>::iterator it = std::find_if(incomplete_jacks_.begin(),
            incomplete_jacks_.end(),
            JackMatcher(jack));
        if (it == incomplete_jacks_.end()) {
            DVLOG(1) << "A non-existing MIDI jack is associated.";
            return false;
        }
        if (current_cable_number_ > 0xf) {
            DVLOG(1) << "Cable number should range from 0x0 to 0xf.";
            return false;
        }
        // CS_ENDPOINT follows ENDPOINT and hence we can use the following
        // member variables.
        it->cable_number = current_cable_number_++;
        it->endpoint_address = current_endpoint_address_;
        jacks->push_back(*it);
        incomplete_jacks_.erase(it);
    }
    return true;
}

void UsbMidiDescriptorParser::Clear()
{
    is_parsing_usb_midi_interface_ = false;
    current_endpoint_address_ = 0;
    current_cable_number_ = 0;
    incomplete_jacks_.clear();
}

} // namespace midi
